In the field of semiconductor manufacturing, inspecting devices and measuring devices using a scanning electron microscope (SEM) have long been used.
As increasingly finer patterns are transferred on a wafer with the evolution of process rule, the density of patterns formed on the wafer also becomes higher, increasing the number of locations requiring evaluation by dimension measurement. As a result, from the viewpoint of reducing the evaluation time, there is a growing demand for narrowing the locations where the risk of defect development is high, i.e., measurement points that require evaluation with higher magnification ratios, by an inspection involving image acquisition with a relatively large field of view (FOV) (acquisition of a low magnification ratio image) relative to the dimension of the pattern as the object of evaluation. In addition to the trend toward formation of ever finer patterns, the dimension of defects to be detected on an image is on a decreasing trend because of the inspection using the low magnification ratio image.
The measuring device is also used for managing exposure conditions for handling process variations, as well as for evaluating the locations of high risk of defect development using an image acquired at high magnification ratio. As the pattern becomes finer, the measurement value variations permitted for managing the pattern dimension for quality management purpose are in a decreasing trend. The amount of variation permitted for exposure conditions for manufacturing non-defective products is also becoming smaller as the pattern becomes finer. Thus, for the purpose of managing exposure conditions too, the permitted variations in measurement values are in a decreasing trend.
Further, as the shape of the pattern transferred on the wafer becomes more complex, the uses are increasing, for both the inspecting device and the measuring device, where evaluation of shape as a two-dimensional feature rather than evaluation of dimension as a one-dimensional feature is required. In the case of shape evaluation, normally, a given contour shape as an evaluation reference and a contour shape extracted from an image obtained by imaging a pattern as the object of evaluation are compared. The comparison is inherently one of different types of data of geometric information and image information. In addition, there is the factor of process variations and the like. Consequently, a phenomenon often develops in which the two contour shapes are different.
Against such background, Patent Literature 1 discloses an example of a technology for performing inspection by contour shape comparison using design data. According to the technology disclosed in Patent Literature 1, the amount of deformation of a pattern is considered separately in terms of a global amount of deformation and a local amount of deformation, and defect inspection is performed using the local amount of deformation.